FFTEC/Vishnu upgrade is the only N54 specific upgrade and full kit available from a vendor. Dudes whining should sell a proven kit themselves at a cheaper price, since currently the only kit is also the cheapest one. FFTEC/Vishnu kit flows a lot better than stock. They have tested the pump in real world and got a competitor to test it in a rig. That is even better than an independent or own testing alone.
It does not make sense for Vishnu to argue with these people who are just jealous and baiting for acquiring more real world information. Rip-off and Duplicate strategy in copying upgraded twins is several months behind the schedule. Based on the whiners' comments and level of N54 fuel system understanding it will take some time before they will have a true upgraded fueling kit to offer, if ever.
For those who want to DIY a fueling upgrade for a stock turbo car and save some money by doing it, I'd suggest either replacing the stock pump with Walbro or a fabbing a kit similar to the FFTEC/Vishnu offering.